Mycobacterium chelonae--a growing problem in soft tissue infection

A Unique Case of Cellulitis Secondary to Mycobacterium chelonae in a Patient With Monoclonal Gammopathy of Undetermined Significance

We report a case of an 84-year-old patient with Monoclonal Gammopathy of Undetermined Significance (MGUS) treated with multiple courses of antibiotics and steroids before being diagnosed with Mycobacterium chelonae infection. It is known that MGUS affects both humoral and cellular immunity with impairment of antibody production, function of T-cells, natural killer (NK) cells, and dendritic cells. This case report demonstrates the need to consider patients with MGUS as immunocompromised and draws attention to the correlation between MGUS and Mycobacterium infections. The delay in diagnosis exemplifies the importance of considering atypical pathogens and involving sub-specialists early in the treatment of infections in patients with a history of MGUS.

Variation among human, veterinary and environmental Mycobacterium chelonae-abscessus complex isolates observed using core genome phylogenomic analysis, targeted gene comparison, and anti-microbial susceptibility patterns

Mycobacterium chelonae is a member of the Mycobacterium chelonae-abscessus complex and a cause of opportunistic disease in fish, reptiles, birds, and mammals including humans. Isolates in the complex are often difficult to identify and have differing antimicrobial susceptibilities. Thirty-one previously identified rapidly-growing, non-tuberculous Mycobacterium sp. isolates cultured from biofilms, fish, reptiles, mammals, including humans, and three ATCC reference strains were evaluated with nine M. chelonae-abscessus complex whole genome sequences from GenBank by phylogenomic analysis, targeted gene comparisons, and in-vitro antimicrobial susceptibility patterns to assess strain variation among isolates from different sources. Results revealed minimal genetic variation among the M. chelonae strains. However, the core genomic alignment and SNP pattern of the complete 16S rRNA sequence clearly separated the turtle type strain ATCC 35752^T from the clinical isolates and human reference strain “M. chelonae chemovar niacinogenes” ATCC 19237, providing evidence of two distinct subspecies. Concatenation of the partial rpoB (752 bp) and complete hsp65 (1,626 bp) sequence produced the same species/subspecies delineations as the core phylogeny. Partial rpoB and hsp65 sequences identified all the clinical isolates to the appropriate species level when respective cut-offs of 98% and 98.4% identity to the M. chelonae type strain ATCC 35752^T were employed. The human strain, ATCC19237, was the most representative strain for the evaluated human, veterinary, and environmental strains. Additionally, two isolates were identified as Mycobacterium saopaulense, its first identification in a non-fish or non-human host.

Mycobacterium chelonae Wrist Infection in an Immunocompetent Patient

We report a 48-year-old Chinese immunocompetent female who presented with right wrist pain and swelling for 9 months because of Mycobacterium chelonae infection of her right wrist. M. chelonae infection has been increasingly reported. Immunocompromised patients are at increased risk of developing such an infection, however, this occasionally occurs in immunocompetent patients. M. chelonae infection more commonly causes cutaneous or soft tissue infection; however, in our case, we found that the infection was so severe that the infective tenosynovial tissue from the volar side of the wrist had eroded through both the volar and dorsal cortex of the distal radius. To our knowledge, wrist tenosynovitis with osteomyelitis of the distal radius caused by M. chelonae is rarely reported, especially in an immunocompetent nontraumatic individual. We successfully treated this patient by repeated surgical debridement using different approaches, appropriate antibiotics, as well as application of antibiotic-loaded cement to fill the bone defect.

Mycobacterium chelonae cutaneous infection in a patient with mixed connective tissue disease

Around 50 mycobacteria species cause human disease. Immunosuppressive states predispose to non-tuberculous mycobaterium infection, such as Mycobacterium chelonae: AFB, non-tuberculous, fast growth of low virulence and uncommon as a human pathogen. It may compromise the skin and soft tissues, lungs, lymph nodes and there is also a disseminated presentation. The diagnosis involves AFB identification and culture on Agar and Lowenstein-Jensen medium base. A 41-year-old female with MCTD (LES predominance) is reported, presenting painless nodules in the right forearm. She denied local trauma. Immunosuppressed with prednisone and cyclophosphamide for 24 months. Lesion biopsy has demonstrated positive bacilloscopy (Ziehl-Neelsen stain) and M.chelonae in culture (Lowenstein-Jensen medium base), therefore clarithromycin treatment has been started (best therapy choice in the literature).

Multiple nontuberculous scrofulodermas showing dramatic response to clarithromycin

Atypical mycobacteria are distinct from the Mycobacterium tuberculosis. Mycobacterium chelonae, a non-pigment producing rapid grower, can be found in many cutaneous sites; infection occurs most commonly after skin trauma from surgery, injections, or minor injuries. In immune competent patients, the infection is more frequently localized as a cellulitis or a nodule, whereas, in the immunocompromised patient, dissemination (more than five lesions) can occur. Because the organism is resistant to antituberculous therapy, abscess can develop and follow a chronic, indolent course. We report a case of multiple scrofuloderma due to nontuberculous infection caused by M. chelonae showing dramatic response to clarithromycin.

Nontuberculous mycobacterial infection after fractionated CO(2) laser resurfacing

Nontuberculous mycobacteria are increasingly associated with cutaneous infections after cosmetic procedures. Fractionated CO2 resurfacing, a widely used technique for photorejuvenation, has been associated with a more favorable side effect profile than alternative procedures. We describe 2 cases of nontuberculous mycobacterial infection after treatment with a fractionated CO2 laser at a private clinic. Densely distributed erythematous papules and pustules developed within the treated area within 2 weeks of the laser procedure. Diagnosis was confirmed by histologic analysis and culture. Both infections responded to a 4-month course of a multidrug regimen. An environmental investigation of the clinic was performed, but no source of infection was found. The case isolates differed from each other and from isolates obtained from the clinic, suggesting that the infection was acquired by postprocedure exposure. Papules and pustules after fractionated CO2 resurfacing should raise the suspicion of nontuberculous mycobacterial infection.

Outbreak of Mycobacterium chelonae infection associated with tattoo ink

BACKGROUND

In January 2012, on the basis of an initial report from a dermatologist, we began to investigate an outbreak of tattoo-associated Mycobacterium chelonae skin and soft-tissue infections in Rochester, New York. The main goals were to identify the extent, cause, and form of transmission of the outbreak and to prevent further cases of infection.

METHODS

We analyzed data from structured interviews with the patients, histopathological testing of skin-biopsy specimens, acid-fast bacilli smears, and microbial cultures and antimicrobial susceptibility testing. We also performed DNA sequencing, pulsed-field gel electrophoresis (PFGE), cultures of the ink and ingredients used in the preparation and packaging of the ink, assessment of source water and faucets at tattoo parlors, and investigation of the ink manufacturer.

RESULTS

Between October and December 2011, a persistent, raised, erythematous rash in the tattoo area developed in 19 persons (13 men and 6 women) within 3 weeks after they received a tattoo from a single artist who used premixed gray ink; the highest occurrence of tattooing and rash onset was in November (accounting for 15 and 12 patients, respectively). The average age of the patients was 35 years (range, 18 to 48). Skin-biopsy specimens, obtained from 17 patients, showed abnormalities in all 17, with M. chelonae isolated from 14 and confirmed by means of DNA sequencing. PFGE analysis showed indistinguishable patterns in 11 clinical isolates and one of three unopened bottles of premixed ink. Eighteen of the 19 patients were treated with appropriate antibiotics, and their condition improved.

CONCLUSIONS

The premixed ink was the common source of infection in this outbreak. These findings led to a recall by the manufacturer.

Mycobacterium chelonae hand infection following ferret bite

We present a case of hand infection caused by Mycobacterium chelonae. The patient was a 58-year-old woman with Type II diabetes mellitus and stage 4 chronic kidney disease. The infection occurred following a ferret bite and had not responded to oral antibiotics in the primary care setting. She developed signs of pyogenic flexor tenosynovitis of the index and middle fingers of her left hand. Laboratory parameters showed high C-reactive protein, raised erythrocyte sedimentation rate and leucocytosis. Ultrasound imaging confirmed the clinical diagnosis. Plain radiographs showed no osseous involvement. The infection was treated with surgical debridement and broad spectrum parenteral antibiotics. The intra-operative tissue specimens were initially negative on aerobic and anaerobic cultures. Following transient improvement of her inflammatory parameters and clinical signs, she developed a recurrence with added features of osteomyelitis of the index and middle finger metacarpal heads on repeat radiographs. A revision surgical debridement of the flexor tenosynovitis and osteomyelitis with specific long-term antibiotic cover has led to resolution of the infection. Extended cultures of the tissue specimens at the regional laboratory confirmed the causative organism to be M. chelonae. To our knowledge, this is the first reported case of M. chelonae infection resulting from a ferret bite. This case reminds us of the need for a high index of suspicion for infection with uncommon pathogens following animal bites, especially in patients with altered immune status.